Infrared Properties of Thin Pt/Al2O3 Granular Metal-Insulator Composite Films. (Reannouncement with New Availability Information).

摘要

The reflection of mid- and near-infrared radiation (400-15000 cm-1 by thin Pt/A1203) cermet films was measured using Fourier transform spectrometer. The data were compared with predictions of three models for the effective optical constants of heterogeneous materials: Maxwell-Garnet, Bruggeman, and a simplified version of a probabilistic growth model due to Sheng. Sheng's model provides the best description of the data over the complete range of metallic volume fraction. This result is expected based on the most likely topology of the films and is in agreement with other work on similar at higher frequencies. The relationship between the microstructural topology, the optical properties of a heterogeneous system, and their description by an homogeneous effective dielectric function has been made clear in recent years. The prediction of the optical response of a granular metal/insulator composite material over the complete range of composition provides an especially stringent challenge to effective medium theories.